Magnetic levitation systems, often called MAGLEV systems, typically take advantage of an electromagnetic interaction between components that are mounted on a vehicle, and components that are mounted on a stationary guideway. The consequence of this interaction is to levitate the vehicle over the guideway. Because the vehicle does not physically contact the guideway during its travel over the guideway, energy losses associated with contact friction are greatly reduced.
One particular system that utilizes the electromagnetic interaction between guideway-mounted components and vehicle-mounted components is disclosed in co-pending, co-owned U.S. patent application Ser. No. 10/330,733 which was filed on Dec. 27, 2002 and is titled “Magnetic Levitation and Propulsion System.” U.S. patent application Ser. No. 10/330,733 (hereinafter the '733 application) is hereby incorporated by reference in its entirety herein. As disclosed in the '733 application, a system for levitating and propelling a vehicle along a stationary guideway includes a linear synchronous motor (LSM) having a component mounted on the vehicle (e.g. a linear array of permanent magnets) and a component mounted on the guideway (e.g. a polyphase winding on an iron core). In combination, these LSM components interact with each other to generate electromagnetic forces for two purposes. For one, the forces act to levitate the vehicle. For another, they act to propel the vehicle along the guideway. It happens that the strength of these LSM forces are strongly dependent on the size of the LSM gap (i.e. the distance between the vehicle-mounted LSM component and the guideway-mounted LSM component).
As further disclosed in the '733 application, the gap between LSM components can be maintained by an electrodynamic system (EDS) having a component that is mounted on the vehicle (e.g. a magnet array), and a component that is mounted on the guideway (e.g. a conductive sheet which is also sometimes called a Litz track). Specifically, the EDS generates electromagnetic forces during movement of the vehicle relative to the guideway that react with the levitation forces created by the LSM. In particular, the forces generated by the EDS maintain the LSM gap within a predetermined operational range. Maintenance of the LSM gap then stabilizes the LSM, and allows the LSM to operate efficiently within a pre-selected range of vehicle speeds.
As implied above, the guideway is an important part of the MAGLEV system. Typically, it is desirable to use a modular guideway design to facilitate guideway construction and simplify the delivery and assembly of the guideway. Functionally, all portions of the guideway must be capable of supporting the weight of the MAGLEV vehicle under all operational conditions. For example, in addition to normal operation, the guideway must also support the MAGLEV vehicle during a power outage or system failure. Further, for applications in high-density urban areas, it is often desirable to elevate the guideway. For these applications, it is desirable that elevated portions of the guideway be lightweight in order to reduce the size and cost of the guideway supporting structures. Moreover, in frigid climates, large guideway structures can cast relatively long shadows which can cause undesirable ice buildups on adjacent roads and roofs. Thus, for some MAGLEV system applications, the size, profile and weight of a guideway structure are all important design considerations.
Other factors that can be important in designing a MAGLEV guideway are the dimensional tolerances of the guideway components and the dimensional stability of the guideway. As indicated above, it is desirable to maintain the gap(s) between vehicle-mounted, and guideway-mounted LSM components within a pre-selected operational range. This, in turn, dictates that relatively tight tolerances be held with regard to the position of guideway-mounted LSM and EDS components and that the modular guideway components fit together closely. Moreover, the specified guideway dimensions must be stable over the life of the guideway and these dimensions must be maintained under typical MAGLEV system loading conditions. More specifically, guideway structures typically require one or more substantially flat surfaces that extend uniformly along the length of the guideway. Applications of these flat guideway surfaces include, but are not limited to, a landing surface for receiving the station/emergency wheels of a MAGLEV vehicle during a vehicle descent, and a structure on which LSM and EDS components can be mounted.
In light of the above, it is an object of the present invention to provide relatively light-weight guideway modules for an elevated MAGLEV guideway and methods for their manufacture. It is another object of the present invention to provide lightweight MAGLEV guideway components that are manufactured to close dimensional tolerances, and that maintain their structural integrity under typical MAGLEV system loading conditions. Yet another object of the present invention is to provide MAGLEV guideway components and methods for their manufacture which are easy to use, relatively simple to implement, and comparatively cost effective.